Th 2017 summer ice minimum was 610,000 sq miles below average as part of an ongoing decline driven by climate change.
Photograph: Lev Fedoseyev/TASS

The Arctic ice cap melted to hundreds of thousands of square miles below average this summer, according to data released late on Tuesday.

Climate change is pushing temperatures up most rapidly in the polar regions and left the extent of Arctic sea ice at 1.79m sq miles at the end of the summer melt season.

This is the time when it reaches its lowest area for the year, before starting to grow again as winter approaches. The 2017 minimum was 610,000 sqmiles below the 1981-2010 average and the eighth lowest year in the 38-year satellite record.

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Ted Scambos at NSIDC said the Arctic sea ice had set a record for the smallest winter extent earlier in 2017 and was on track to be close to the 2012 record minimum until July. But a cloudy and cooler than normal August slowed the melting.

The 2017 sea ice level fits with an overall steady decline over the decades, but one that varies from year to year, Scambos said. “It’s not going to be a staircase heading down to zero every year,” he said. “[But] the Arctic will continue to evolve towards less ice. There’s no dodging that.”

Rod Downie, head of polar programmes at WWF, said: “From space, the loss of Arctic sea ice is the clearest and most visible sign of climate change, and human beings are responsible for most of it. We are engineering our planet and its climate.”

“That’s not good for the people of the Arctic who depend upon sea ice for their traditional way of life and for people across the world who depend on a stable climate,” he said. The Arctic could be virtually free of ice in summer within people’s lifetimes, he warned, and called for more action on climate change by reducing carbon emissions.